The Mets are getting right-handed pitchers Sean Reid-Foley, Yennsy Diáz and Josh Winckowski in the trade.
Matz, a 29-year-old left-hander, agreed to a one-year, $5.2 million contract with the Mets in December.
Matz reflected on the trade Thursday in a series of tweets.
I'm excited for the opportunity to join the @BlueJays and one of the most exciting teams in the game! I'm pumped to do my part to help this team get back to the playoffs and you're going to get everything I've got!— Steven Matz (@Smatz88) January 28, 2021
I'll always be grateful to the Mets for the opportunity to play for my hometown team. Thank you to Mets fans for all your support throughout my time in NY. And thanks to all my teammates and coaches - I wish you all nothing but the best of luck moving forward!— Steven Matz (@Smatz88) January 28, 2021
That deal came after he had the poorest of his six seasons, going 0-5 with a 9.68 ERA while earning $1,851,852 in prorated pay from a $5 million salary. He was dropped from the rotation after starting 0-4 with a 9.00 ERA in five starts then made three relief appearances along with a spot start.
Matz is 31-41 with a 4.35 ERA over 107 career starts and five relief appearances.
The Blue Jays have had a busy offseason, highlighted by the addition of outfielder George Springer on a six-year, $150 million deal. Earlier this week, infielder Marcus Semien reached agreement on a one-year, $18 million contract, a source familiar with the deal told ESPN's Jeff Passan.
The Mets added a left-hander to its bullpen earlier in the day, agreeing to a one-year contract with free agent Aaron Loup, according to multiple reports. The deal was subject to a successful physical.
Loup's pending arrival made Matz more expendable, and the trade with Toronto capped an eventful day that began with the Mets promoting recently hired assistant general manager Zack Scott to acting GM -- eight days after Jared Porter was fired from that job.
Reid-Foley was 1-0 with a 1.35 ERA in five relief outings covering 6 2/3 innings for the Blue Jays last season. The 25-year-old right-hander, a second-round draft pick in 2014, is 5-8 with a 4.40 ERA in 21 major league games -- including 13 starts -- over three seasons with Toronto. He has 76 strikeouts in 71 2/3 innings and is not eligible for arbitration until after the 2022 season at the earliest.
Winckowski, 22, was a combined 10-8 with a 2.69 ERA at Class A Dunedin and Class A Lansing in 2019. The 15th-round draft pick was rated Toronto's 27th-best prospect in 2020, according to MLB.com. He is 18-17 with a 3.35 ERA in 54 games (50 starts) across four minor league seasons.
Diaz, 24, appeared in one big league game for the Blue Jays in 2019. He was 11-9 with a 3.74 ERA in 26 games (24 starts) for Double-A New Hampshire that year and was rated the Blue Jays' 26th-best prospect in 2020 by MLB.com. Diaz is 34-26 with a 3.84 ERA over five minor league seasons.
The Associated Press contributed to this report.